From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 75722CEFC5D for ; Wed, 9 Oct 2024 10:19:51 +0000 (UTC) Received: from list by lists.xenproject.org with outflank-mailman.814285.1227820 (Exim 4.92) (envelope-from ) id 1syTn3-0003bk-Ax; Wed, 09 Oct 2024 10:19:33 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 814285.1227820; Wed, 09 Oct 2024 10:19:33 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1syTn3-0003bd-8Q; Wed, 09 Oct 2024 10:19:33 +0000 Received: by outflank-mailman (input) for mailman id 814285; Wed, 09 Oct 2024 10:19:32 +0000 Received: from se1-gles-sth1-in.inumbo.com ([159.253.27.254] helo=se1-gles-sth1.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1syTn2-0003bX-9P for xen-devel@lists.xenproject.org; Wed, 09 Oct 2024 10:19:32 +0000 Received: from mail-ej1-x634.google.com (mail-ej1-x634.google.com [2a00:1450:4864:20::634]) by se1-gles-sth1.inumbo.com (Halon) with ESMTPS id f8e8283e-8627-11ef-a0bd-8be0dac302b0; Wed, 09 Oct 2024 12:19:31 +0200 (CEST) Received: by mail-ej1-x634.google.com with SMTP id a640c23a62f3a-a9951fba3b4so479450366b.1 for ; Wed, 09 Oct 2024 03:19:31 -0700 (PDT) Received: from [10.156.60.236] (ip-037-024-206-209.um08.pools.vodafone-ip.de. [37.24.206.209]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-a994483e1e3sm520924766b.111.2024.10.09.03.19.30 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 09 Oct 2024 03:19:30 -0700 (PDT) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: f8e8283e-8627-11ef-a0bd-8be0dac302b0 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=google; t=1728469170; x=1729073970; darn=lists.xenproject.org; h=content-transfer-encoding:in-reply-to:autocrypt:from :content-language:references:cc:to:subject:user-agent:mime-version :date:message-id:from:to:cc:subject:date:message-id:reply-to; bh=YWNOkMJt/qZiHUSsIWHQpYMnVYXyjbu1ne9rUwtjF38=; b=SbIH1/3cbc0z2qdRVsvSo5ozlDZOjM66Sa0pIqwULH4z7jhv3GzQhOwtbO7k5Q16Ag bl1BpCM8wm6wjx06IULW+O/+cvgeWr7c86kn33rwPfSL1FNGwl0qdwflA1krLiVBI+6Z DFTuyNr48SpGfwkp3l1xMOmDYdlb85aijnUGsj9zb1DpZLuGrkBO2ak3h5VwxyvllPGW lEH3VnCWpF4Z5qc19+SmNDRFh0brXyUQ2Wx52qUKHt5Uo3fRldrqHGUQBs0m8K7g7+HY A0i8bT+br7V87qCfLgyC92poYLfh7L8jlXVdc2qp2fh9VoFpXaSDlkpFjJaiFzwn8pK2 XXsQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1728469170; x=1729073970; h=content-transfer-encoding:in-reply-to:autocrypt:from :content-language:references:cc:to:subject:user-agent:mime-version :date:message-id:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=YWNOkMJt/qZiHUSsIWHQpYMnVYXyjbu1ne9rUwtjF38=; b=qAri6ivLOTdZ3wkbiY4UIlqWRaEKu51fjCIghGL8MF32EBVKypxTppWGiLpUHv6dh2 IEZlLkCvN+e7i212koUW5IrenY/S0aia5RU4xVYppLKTKDNi7TIWCHVioTcXgmG4Op0T FG8gYmN1cEz2wchVy3/BBoWBYLM5HIfFdKFXgXz+rEJsX8qmJRMva6C12X+ioIBHKwys PX9EjFWodDAsQNrOOuA2yYg15T364q5XbPbOwN5us6bZ/btgwi1SX1Kk36MNybTbdnGi Nz6vuUbi7B0Ei/qN8Z7FESVfvsQVrsttt7PY+Ac95eCv+WwjS+dwfIV1r0ukBODmpTxt WD4w== X-Forwarded-Encrypted: i=1; AJvYcCXU4edDMWvl2l0c/FRfo+d/LhJd9FvVmIVExsNeQw8Fqndqq9kozPoQ3OjXdOviQPUZ02Fi8BCxpBw=@lists.xenproject.org X-Gm-Message-State: AOJu0YwJ3/mXzn0gnVM9x4WIrHAow31vqcaKv3tKkp1qy++zG54EBG5x +NbWltGOb7vmOo34whpwzh8SM/rXYqgDibQdp1R3qIo6FdoWLiRI1n8V3Hkr1w== X-Google-Smtp-Source: AGHT+IHgnMfKMSWpUDB9fN6tQbby353vUU0Y9RU7f24ZjPlvVMjwIm+vwuVzVrCNbLqr9J6lq1TVgQ== X-Received: by 2002:a17:907:d3cc:b0:a99:7e67:cd13 with SMTP id a640c23a62f3a-a998d208896mr171984766b.36.1728469170533; Wed, 09 Oct 2024 03:19:30 -0700 (PDT) Message-ID: <00ac0665-e4ff-4a56-8537-e81573710c3c@suse.com> Date: Wed, 9 Oct 2024 12:19:29 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] tools/xg: increase LZMA_BLOCK_SIZE for uncompressing the kernel To: =?UTF-8?Q?Marek_Marczykowski-G=C3=B3recki?= Cc: Anthony PERARD , Juergen Gross , xen-devel@lists.xenproject.org References: <20241008213225.728922-1-marmarek@invisiblethingslab.com> <226bc9b3-6741-4cb6-917b-1164e340a19d@suse.com> Content-Language: en-US From: Jan Beulich Autocrypt: addr=jbeulich@suse.com; keydata= xsDiBFk3nEQRBADAEaSw6zC/EJkiwGPXbWtPxl2xCdSoeepS07jW8UgcHNurfHvUzogEq5xk hu507c3BarVjyWCJOylMNR98Yd8VqD9UfmX0Hb8/BrA+Hl6/DB/eqGptrf4BSRwcZQM32aZK 7Pj2XbGWIUrZrd70x1eAP9QE3P79Y2oLrsCgbZJfEwCgvz9JjGmQqQkRiTVzlZVCJYcyGGsD /0tbFCzD2h20ahe8rC1gbb3K3qk+LpBtvjBu1RY9drYk0NymiGbJWZgab6t1jM7sk2vuf0Py O9Hf9XBmK0uE9IgMaiCpc32XV9oASz6UJebwkX+zF2jG5I1BfnO9g7KlotcA/v5ClMjgo6Gl MDY4HxoSRu3i1cqqSDtVlt+AOVBJBACrZcnHAUSuCXBPy0jOlBhxPqRWv6ND4c9PH1xjQ3NP nxJuMBS8rnNg22uyfAgmBKNLpLgAGVRMZGaGoJObGf72s6TeIqKJo/LtggAS9qAUiuKVnygo 3wjfkS9A3DRO+SpU7JqWdsveeIQyeyEJ/8PTowmSQLakF+3fote9ybzd880fSmFuIEJldWxp Y2ggPGpiZXVsaWNoQHN1c2UuY29tPsJgBBMRAgAgBQJZN5xEAhsDBgsJCAcDAgQVAggDBBYC AwECHgECF4AACgkQoDSui/t3IH4J+wCfQ5jHdEjCRHj23O/5ttg9r9OIruwAn3103WUITZee e7Sbg12UgcQ5lv7SzsFNBFk3nEQQCACCuTjCjFOUdi5Nm244F+78kLghRcin/awv+IrTcIWF hUpSs1Y91iQQ7KItirz5uwCPlwejSJDQJLIS+QtJHaXDXeV6NI0Uef1hP20+y8qydDiVkv6l IreXjTb7DvksRgJNvCkWtYnlS3mYvQ9NzS9PhyALWbXnH6sIJd2O9lKS1Mrfq+y0IXCP10eS FFGg+Av3IQeFatkJAyju0PPthyTqxSI4lZYuJVPknzgaeuJv/2NccrPvmeDg6Coe7ZIeQ8Yj t0ARxu2xytAkkLCel1Lz1WLmwLstV30g80nkgZf/wr+/BXJW/oIvRlonUkxv+IbBM3dX2OV8 AmRv1ySWPTP7AAMFB/9PQK/VtlNUJvg8GXj9ootzrteGfVZVVT4XBJkfwBcpC/XcPzldjv+3 HYudvpdNK3lLujXeA5fLOH+Z/G9WBc5pFVSMocI71I8bT8lIAzreg0WvkWg5V2WZsUMlnDL9 mpwIGFhlbM3gfDMs7MPMu8YQRFVdUvtSpaAs8OFfGQ0ia3LGZcjA6Ik2+xcqscEJzNH+qh8V m5jjp28yZgaqTaRbg3M/+MTbMpicpZuqF4rnB0AQD12/3BNWDR6bmh+EkYSMcEIpQmBM51qM EKYTQGybRCjpnKHGOxG0rfFY1085mBDZCH5Kx0cl0HVJuQKC+dV2ZY5AqjcKwAxpE75MLFkr wkkEGBECAAkFAlk3nEQCGwwACgkQoDSui/t3IH7nnwCfcJWUDUFKdCsBH/E5d+0ZnMQi+G0A nAuWpQkjM1ASeQwSHEeAWPgskBQL In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 09.10.2024 11:52, Marek Marczykowski-Górecki wrote: > On Wed, Oct 09, 2024 at 09:19:57AM +0200, Jan Beulich wrote: >> On 08.10.2024 23:32, Marek Marczykowski-Górecki wrote: >>> --- a/tools/libs/guest/xg_dom_bzimageloader.c >>> +++ b/tools/libs/guest/xg_dom_bzimageloader.c >>> @@ -272,8 +272,7 @@ static int _xc_try_lzma_decode( >>> return retval; >>> } >>> >>> -/* 128 Mb is the minimum size (half-way) documented to work for all inputs. */ >>> -#define LZMA_BLOCK_SIZE (128*1024*1024) >>> +#define LZMA_BLOCK_SIZE (256*1024*1024) >> >> That's as arbitrary as before, now just not even with a comment at least >> hinting at it being arbitrary. Quoting from one of the LZMA API headers: >> >> * Decoder already supports dictionaries up to 4 GiB - 1 B (i.e. >> * UINT32_MAX), so increasing the maximum dictionary size of the >> * encoder won't cause problems for old decoders. >> >> IOW - what if the Linux folks decided to increase the dictionary size >> further? I therefore wonder whether we don't need to make this more >> dynamic, perhaps by peeking into the header to obtain the dictionary >> size used. The one thing I'm not sure about is whether there can't be >> multiple such headers throughout the file, and hence (in principle) >> differing dictionary sizes. > > What is the purpose of this block size limit? From the error message, it > seems to be avoiding excessive memory usage during decompression (which > could be DoS via OOM). If that's the case, then taking the limit from > the kernel binary itself will miss this point (especially in case of > pygrub or similar, but there may be other cases of not-fully-trusted > kernel binaries). Indeed. The question then simply is: Where do we want to draw the line between what we permit and what we reject? Jan